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Anaphylaxis definition: An acute hypersensitivity reaction due to exposure to a previously encountered ANTIGEN. The reaction may include rapidly progressing URTICARIA, respiratory distress, vascular collapse, systemic SHOCK, and death.
anaphylaxis definition: a manifestation of immediate hypersensitivity in which exposure of a sensitized individual to a specific antigen or hapten results in urticaria, pruritis and angioedema, followed by vascular collapse and shock often accompanied by life threatening respiratory distress.
Shock, Anaphylactic definition: Systemic anaphylaxis is the most dramatic example of an immediate hypersensitivity reaction; is uncommon and unexpected in nature and occasionally results in a fatal outcome.
Shock, Anaphylactic definition: Pertaining to anaphylaxis.
Anaphylactic Shock definition: An acute inflammatory reaction resulting from the release of histamine and histamine-like substances from mast cells, causing a hypersensitivity immune response. Clinically, it presents with breathing difficulty, dizziness, hypotension, cyanosis and loss of consciousness, and may lead to death.
anaphylaxis definition: OBSOLETE. Extreme immunological sensitivity of the body or tissues to the reintroduction of an antigen. It is a form of anamnestic reaction and is accompanied by pathological changes in tissues or organs due to the release of pharmacologically active substances. [ISBN:0198506732 "Oxford Dictionary of Biochemistry and Molecular Biology"]
Antigen-Antibody Reactions definition: The processes triggered by interactions of ANTIBODIES with their ANTIGENS.
antigen antibody reaction definition: immune response induced by binding antigen to antibody.
Biuret Reaction definition: A reaction characterized by a violet color upon the addition of copper sulfate to all compounds with two amide or peptide bonds linked directly or through an intermediate carbon atom. Used in the detection and estimation of proteins and peptides having more than two amino acids.
Conversion Disorder definition: A disorder whose predominant feature is a loss or alteration in physical functioning that suggests a physical disorder but that is actually a direct expression of a psychological conflict or need.
Cross Reactions definition: Serological reactions in which an antiserum against one antigen reacts with a non-identical but closely related antigen.
decidualization definition: The cellular and vascular changes occurring in the endometrium of the pregnant uterus just after the onset of blastocyst implantation. This process involves the proliferation and differentiation of the fibroblast-like endometrial stromal cells into large, polyploid decidual cells that eventually form the maternal component of the placenta. [http://cancerweb.ncl.ac.uk/, ISBN:0721662544 "Dorland's Illustrated Medical Dictionary", PMID:11133685]
Dissociative Disorders definition: Sudden temporary alterations in the normally integrative functions of consciousness.
Echolalia definition: Involuntary ("parrot-like"), meaningless repetition of a recently heard word, phrase, or song. This condition may be associated with transcortical APHASIA; SCHIZOPHRENIA; or other disorders. (From Adams et al., Principles of Neurology, 6th ed, p485)
Escape Reaction definition: Innate response elicited by sensory stimuli associated with a threatening situation, or actual confrontation with an enemy.
escape reaction definition: innate response elicited by sensory stimuli associated with a threatening situation, or actual confrontation with an enemy.
False Negative Reactions definition: Negative test results in subjects who possess the attribute for which the test is conducted. The labeling of diseased persons as healthy when screening in the detection of disease. (Last, A Dictionary of Epidemiology, 2d ed)
False Positive Reactions definition: Positive test results in subjects who do not possess the attribute for which the test is conducted. The labeling of healthy persons as diseased when screening in the detection of disease. (Last, A Dictionary of Epidemiology, 2d ed)
Hypersensitivity definition: Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.
hypersensitivity definition: state of previously immunized body in which tissue damage results from the immune response to a further dose of antigen.
Allergy definition:

Hypersensitivity to an agent caused by an immunologic response to an initial exposure

Hypersensitivity definition: Hypersensitivity; a local or general reaction of an organism following contact with a specific allergen to which it has been previously exposed and to which it has become sensitized.
hypersensitivity definition: An exaggerated response by the immune system to a drug or other substance.
hypersensitivity definition: An inflammatory response to an exogenous environmental antigen or an endogenous antigen initiated by the adaptive immune system. [GOC:jal, ISBN:0781735149 "Fundamental Immunology"]
Hypersensitivity definition: A local or general reaction of an organism following contact with a specific allergen to which it has been previously exposed and to which it has become sensitized.
Immune Adherence Reaction definition: A method for the detection of very small quantities of antibody in which the antigen-antibody-complement complex adheres to indicator cells, usually primate erythrocytes or nonprimate blood platelets. The reaction is dependent on the number of bound C3 molecules on the C3b receptor sites of the indicator cell.
immune adherence reaction definition: a method for the detection of very small quantities of antibody in which the antigen-antibody-complement complex adheres to indicator cells, usually primate erythrocytes or nonprimate blood platelets; reaction is dependent on the number of bound C3 molecules on the C3b receptor sites of the indicator cell.
Leukemoid Reaction definition: A peripheral blood picture resembling that of leukemia or indistinguishable from it on the basis of morphologic appearance alone. (Dorland, 27th ed)
Lymphocyte Culture Test, Mixed definition: Measure of histocompatibility at the HL-A locus. Peripheral blood lymphocytes from two individuals are mixed together in tissue culture for several days. Lymphocytes from incompatible individuals will stimulate each other to proliferate significantly (measured by tritiated thymidine uptake) whereas those from compatible individuals will not. In the one-way MLC test, the lymphocytes from one of the individuals are inactivated (usually by treatment with MITOMYCIN or radiation) thereby allowing only the untreated remaining population of cells to proliferate in response to foreign histocompatibility antigens.
mixed lymphocyte reaction test definition: measure of histocompatibility at the HLA locus: peripheral blood lymphocytes from two individuals are mixed together in tissue culture for several days; lymphocytes from incompatible individuals will stimulate each other to proliferate significantly (measured by tritiated thymidine uptake) whereas those from compatible individuals will not; in the one-way MLC test, the lymphocytes from one of the individuals are inactivated thereby allowing only the untreated remaining population of cells to proliferate in response to foreign histocompatibility antigens.
Mixed Lymphocyte Reaction Test definition: Measure of histocompatibility at the HL-A locus. Peripheral blood lymphocytes from two individuals are mixed together in tissue culture for several days. Lymphocytes from incompatible individuals will stimulate each other to proliferate significantly (usually measured by tritiated thymidine uptake) whereas those from compatible individuals will not. In the one-way MLC test, the lymphocytes from one of the individuals are inactivated (usually by treatment with mitomycin C or radiation) thereby allowing only the untreated remaining population of cells to proliferate in response to foreign histocompatibility antigens.
Meningism definition: A condition characterized by neck stiffness, headache, and other symptoms suggestive of meningeal irritation, but without actual inflammation of the meninges (MENINGITIS). Spinal fluid pressure may be elevated but spinal fluid is normal. (DeJong, The Neurologic Examination, 4th ed, p673)
Meningismus definition: The symptoms of neck stiffness, headache, and photophobia resulting from meningeal irritation. Causes include subarachnoid hemorrhage and acute febrile diseases.
Periodic Acid-Schiff Reaction definition: A histochemical technique for staining carbohydrates. It is based on PERIODIC ACID oxidation of a substance containing adjacent hydroxyl groups. The resulting aldehydes react with Schiff reagent to form a colored product.
Polymerase Chain Reaction definition: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.
polymerase chain reaction definition: method for reproducing specific DNA sequences based on elongation of complementary primers by DNA polymerase; primarily used to increase quantities for analytical detection of, e.g., virus genome.
polymerase chain reaction definition: A laboratory method used to make many copies of a specific DNA sequence.
Polymerase Chain Reaction definition: A method for amplifying a DNA base sequence using multiple rounds of heat denaturation of the DNA and annealing of oligonucleotide primers complementary to flanking regions in the presence of a heat-stable polymerase. This results in duplication of the targeted DNA region. Newly synthesized DNA strands can subsequently serve as additional templates for the same primer sequences, so that successive rounds of primer annealing, strand elongation, and dissociation produce rapid and highly specific amplification of the desired sequence. PCR also can be used to detect the existence of the defined sequence in a DNA sample.
Polymerase chain reaction definition: Molecular, Polymerase chain reaction
Prussian Blue Reaction definition: The reaction of potassium ferrocyanide with ferric iron to yield a dark blue precipitate at the sites of the ferric iron. Used to determine ferric iron in tissues, particularly in the diagnosis of disorders of iron metabolism.
Retrograde Degeneration definition: Pathologic changes that occur in the axon and cell body of a neuron proximal to an axonal lesion. The process is characterized by central chromatolysis which features flattening and displacement of the nucleus, loss of Nissl bodies, and cellular edema. Central chromatolysis primarily occurs in lower motor neurons.
axon reaction definition: series of changes in the ganglion cell following the severing of its axon.
Shwartzman Phenomenon definition: Hemorrhagic necrosis that was first demonstrated in rabbits with a two-step reaction, an initial local (intradermal) or general (intravenous) injection of a priming endotoxin (ENDOTOXINS) followed by a second intravenous endotoxin injection (provoking agent) 24 h later. The acute inflammation damages the small blood vessels. The following intravascular coagulation leads to capillary and venous THROMBOSIS and NECROSIS. Shwartzman phenomenon can also occur in other species with a single injection of a provoking agent, and during infections or pregnancy. Its susceptibility depends on the status of IMMUNE SYSTEM, coagulation, FIBRINOLYSIS, and blood flow.
Shwartzman phenomenon definition: vasculitis, local or systemic, caused by a two-stage reaction in which a first encounter with endotoxin produces intravascular fibrin thrombi whose clearance results in reticuloendothelial blockade which prevents the clearance of thrombi caused by a second encounter with endotoxin, (or a variety of polyanions, glycogen or antigen/antibody complexes) resulting in tissue necrosis and/or hemorrhage; in pregnancy gram-negative septicemia during delivery or abortion may serve as the first or provocative encounter.
Startle Reaction definition: A complex involuntary response to an unexpected strong stimulus usually auditory in nature.
startle reaction definition: complex involuntary response to an unexpected strong stimulus usually auditory in nature.
drug adverse effect definition: unintended, deleterious effects of otherwise licit, therapeutic, properly administered drugs; for effects of illicit and abused drugs, or of environmental chemicals, see TOXICOLOGY or POISONING.
response to stress definition: A change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a disturbance in organismal or cellular homeostasis, usually, but not necessarily, exogenous (e.g. temperature, humidity, ionizing radiation). [GOC:mah]
Heat-Shock Response definition: A constellation of responses that occur when an organism is exposed to excessive heat and other environmental stressors. Responses include synthesis of some proteins, repression of other proteins, and expression of new proteins. (From Segen, Dictionary of Modern Medicine, 1992)
Heat-Shock Response definition: A constellation of responses that occur when an organism is exposed to excessive heat and other environmental stresses. Responses include synthesis of some proteins, repression of other proteins, and expression of new proteins. (From Segen, Dictionary of Modern Medicine, 1992)
Adverse Reaction definition:

Indicates that the observation is of an unexpected negative occurrence in the subject suspected to result from the subject's exposure to one or more agents. Observation values would be the symptom resulting from the reaction.

Adverse Reaction definition: Any noxious and unintended response(s) to a medical product or procedure, for which a causal relationship with this product or procedure is at least a reasonable possibility i.e., the relationship cannot be ruled out.
acrosome reaction definition: The discharge, by sperm, of a single, anterior secretory granule following their attachment to the zona pellucida surrounding the oocyte. The process begins with the fusion of the outer acrosomal membrane with the sperm plasma membrane and ends with the disperasl of the acrosomal contents into the egg. [GOC:dph, PMID:3886029]
Acrosome Reaction definition: Changes that occur to liberate the enzymes of the ACROSOME of a sperm (SPERMATOZOA). Acrosome reaction allows the sperm to penetrate the ZONA PELLUCIDA and enter the OVUM during FERTILIZATION.
Ligase Chain Reaction definition: A DNA amplification technique based upon the ligation of OLIGONUCLEOTIDE PROBES. The probes are designed to exactly match two adjacent sequences of a specific target DNA. The chain reaction is repeated in three steps in the presence of excess probe: (1) heat denaturation of double-stranded DNA, (2) annealing of probes to target DNA, and (3) joining of the probes by thermostable DNA ligase. After the reaction is repeated for 20-30 cycles the production of ligated probe is measured.
Ligase Chain Reaction definition: Molecular, Ligase Chain Reaction
photosynthesis, dark reaction definition: A complex cycle of enzyme-mediated reactions which catalyzes the reduction of carbon dioxide to sugar. As well as carbon dioxide the cycle requires reducing power in the form of reduced nicotinamide adenine dinucleotide phosphate (NADP) and chemical energy in the form of adenosine triphosphate (ATP). The reduced NADP (NADPH) and ATP are produced by the 'light' reactions. [ISBN:0582015952]
Freezing Reaction, Cataleptic definition: An induced response to threatening stimuli characterized by the cessation of body movements, except for those that are involved with BREATHING, and the maintenance of an immobile POSTURE.
biochemical reactions definition: In living cells, chemical reactions that help sustain life and allow cells to grow.
Biochemical Reaction definition: A chemical process, typically mediated by an enzyme, in which one or more substances (a substrate) are transformed by covalent modification into another substance(s) (a product) or in which the state of a substance is transformed.
Radiation Recall Dermatitis definition: Acute skin manifestations at the site of previous exposure to ionizing radiation. It is triggered by the administration of certain drugs days or years after the initial radiation exposure.
Radiation-Recall Dermatitis definition: Acute skin inflammatory reaction caused by drugs, especially chemotherapeutic agents, weeks or months following radiotherapy. The inflammatory reaction is confined to the previously irradiated skin and the symptoms disappear after the removal of the pharmacologic agent.